A lot of times foods have 1-3 nutrients that are 'enhanced' through cooking, however you are still destroying the other 98% of nutrients through cooking.
Are you certain it is not the exact opposite?
Green tea is not cooked at high temps, it is steeped at just below boiling so it does not get heated beyond 210-212 degrees F. Heck, I was in a sauna yesterday for probably 1/2 hour that was 170 degrees.
I'm not certain of the exact percentages, just noticing that people tend to be concerned about 1 or 2 nutrients that are enhanced with cooking over the rest that aren't.
I believe green tea leaves are roasted at high temps during processing. White tea is usually sun dried though.
Maybe you could be in a sauna at 170 degrees for a small period of time, but you likely couldn't put your hand in 170 degree water for even a few seconds without it getting destroyed. Most people cannot even handle being in the heat very long when it's over 90 degrees.